The present invention relates to a method for ascertaining the effectiveness of cooling the withdrawal rollers in a continuous casting machine, particularly a machine for continuous casting of steel.
Upon continuously casting steel ingots, the ingot as emerging from the bottom of the mold has a solidified skin or shell while the interior of the ingot is still liquidous. The shell is, of course, subjected to a ferrostatic pressure because the liquidous steel in the withdrawn ingot still communicates with the molten bath in the mold and, therefore, is subjected to the ferrostatic pressure of that entire liquid column. Therefore, the ingot and particularly the pressurized skin or shell thereof, has to be supported by rollers which also withdraw the ingot from the mold. Of course, it is necessary to make sure that the rollers do not damage the skin of the ingot. Therefore, these rollers must run smoothly and centrally without wobbling.
The rollers employed in continuous casting stands are usually required to be water cooled, particularly from the inside. Moreover, cooling must occur at a particular rate, and it is a requirement for such a system to make sure that the rolls are continuously being cooled at that rate. Otherwise, a high temperature may damage the rollers in some fashion. For example, hot bearings will wear rapidly; otherwise unimportant flaws may become more pronounced; and the rolls may bend.
It is customary to connect these support rollers in groups to a suitable conduit for the coolant, i.e. a source of water, and the flow of water is continuously monitored. Should a water feed path to or even in a roller be defective, clogged or otherwise impeded, it is difficult to ascertain the deficiency in cooling of that particular roller because the sum total of the amount of water fed to the group may vary only insignificantly. Moreover, small deviations in the coolant flow cannot be used directly as an indication for the cooling (or lack of it) of an individual roller. The obvious solution to this problem is to provide each roller with its own supervising equipment as to the flow of water. However, that approach is abviously very expensive.